An Identicon is a visual representation of a hash value, usually of an IP address, that serves to identify a user of a computer system as an effectively random form of avatar while protecting the user's privacy. The original Identicon was a 9-block graphic, and the representation has been extended to other graphic forms by third parties.
Invention
Don Park came up with the Identicon idea on January 18, 2007. In his words:
A similar method had previously been described by Adrian Perrig and Dawn Song in their 1999 publication on hash visualization,Perrig, Adrian, and Dawn Song. "Hash visualization: A new technique to improve real-world security." International Workshop on Cryptographic Techniques and E-Commerce. Vol. 25. 1999. which had already seen wide use such as in the random art of SSH keys.
Applications
GitHub and Roll20 both use identicons to visually differentiate users who have not set their own avatar. Wikis and blogs may generate identicons to visually identify authors based on IP addresses. This provides some protection against impersonation without requiring authentication. Third-party software is available to generate identicons for the purposes of identifying eBay sellers.Munnin [ Product - Identicon ] Quick seller identification in the item listing The original Identicon idea has been expanded to include a couple of new, simple yet very effective, anti-phishing protection schemes. One of them requires client-side support; Park is interested in talking to browser vendors regarding its incorporation. He calls this expansion "Gemini."
References
External links Don Park's original source code at GitHub Mavenized project based on Don Park's original source code at GitHub Identicons as Visual Fingerprints by Phil Haack PHP-Identicons Identicon CFC - ColdFusion implementation of Identicons NIdenticon - .Net implementation of Identicons Awesome Identicon - A curated list of identicon examples